2. Technical Field of the Invention
The present invention generally relates to a body cavity pressure adjusting device which is adapted to automatically adjust the pressure in a body cavity (hereinafter referred to as "body cavity pressure ") during a medical examination or treatment with an endoscope. The present invention also relates to a device for treating a diseased part of a body cavity with a laser beam, and more specifically, to a laser knife which utilizes gas flow into a body cavity in order to prevent adhesion of foreign matter to the laser knife.
2. Background of the Invention
Laser medical treament devices known as laser knives are known which are adapted to use gas flow into a body cavity to prevent adhesion of foreign matter to a laser knife. When used to treat the diseased portion of a body cavity, a laser power transmitting fiber (hereinafter referred to as a "laser fiber") is inserted into the body cavity through the channel or tube of an endoscope. If foreign substances scattered from the diseased part of the body stick to the end portion of the laser fiber, then the laser fiber can be thermally damaged. In order to overcome this difficulty, a laser fiber is inserted into a protective pipe of a larger diameter, and gas is jetted under pressure through the gap between the laser fiber and the protective pipe and into the body cavity. This method is generally employed in order to prevent the adhesion of foreign substances to the laser fiber.
When such a device is utilized to treat the diseased portion of a stomach, the stomach becomes filled with gas supplied through the gap between the protective pipe and the laser fiber. Therefore, the stomach wall is sometimes spread so that thin veins become broken and are caused to bleed, or the stomach may be abnormally strained, thereby causing a patient to suffer pain. Further, if the stomach wall spreads, small variations of the mucous membranes cannot be correctly diagnosed and treated with the endoscope. Accordingly, it is essential to recover gas supplied into the stomach in order to maintain the pressure in the stomach within a predetermined range of values at all times.
For this purpose, a two-channel endoscope has previously been utilized in such a manner that one of the two channels is used for the laser fiber and the other is used to discharge gas from the body cavity. However, such a two-channel endoscope is disadvantageous in that the insertion pipe is large in diameter, and, when it is inserted into the body cavity, the patient suffers pain. On the other hand, in order to discharge gas supplied by a one-channel endoscope, a pipe such as a stomach sonde must additionally be inserted into the stomach. In such a case, not only is the patient's pain increased, but also the amount of operator labor required is also increased.
During medical examination or treatment with an endoscope, air is generally supplied into a body cavity such as the stomach in order to spread the walls of the body cavity or to clean the objective lens of the endoscope.
Generally, a body cavity internal organ, such as the stomach or intestine, automatically contracts itself. Therefore, during medical examination of a body cavity with an endoscope, gas such as air is supplied into the body cavity through a gas supply pipe line which is built into the endoscope in order to inflate the body cavity so that the operator can adequately observe the body cavity. However, as the stomach becomes excessively filled with air, then a number of difficulties as set forth hereinafter are caused. For example, the gastric wall may be so greatly spread that small blood vessels become broken, with the result that the stomach will hemorrhage. As the stomach is greatly strained, the patient may belch. As a result, supplying air into the stomach inflicts pain on the patient. Since the gastric wall may be excessively spread, as described above, it is difficult to accurately detect delicate changes in the mucous membranes, with the result that the diagnosis or medical treatment of gastritis under the endoscope is not always correct.
In order to eliminate the above-described difficulties, the following method has been used. The forceps channel of the endoscope is connected, through a manual valve, with a suction device (or a suction bottle). The operator operates the manual valve while watching the patient so that pressure within the body cavity will not become excessively high. However, for instance during the medical examination of a large intestine, excessive increases in pressure in the large intestine are hazardous because the wall of the large intestine is weaker than the gastric wall. Particularly in the case of a patient who is liable to hesitate to complain because of pain, the worse case which may occur is that the wall of the large intestine will be broken.
In any case, in conventional medical examination with endoscopes, suppression or control of the increase of body cavity pressure is effected according to the experience of the operator. The idea of maintaining the pressure in a body cavity constant has not been utilized.
Even if a pressure detector for detecting pressure in the suction pipeline of an endoscope would be provided to detect the pressure in the body cavity through the suction pipeline, and a suction device connected to the suction pipeline would be operated in response to the output signal of the pressure detector in order to suck gas out of the body cavity, there would be a resulting automatic decrease in pressure in the body cavity; in such an operation, however, not only air but mucous, blood and other debris are sucked into the suction pipeline of the endoscope, and they often may clog up the suction pipeline. In such a case, the pressure in the body cavity will no longer be detected by the pressure detector in such a body cavity pressure adjusting device with a pressure sensor. Therefore, even when the pressure in the body cavity has increased, suction will not be effected. Accordingly, it is impossible for the operator to observe the mucous membrane in detail, and the inner wall of the body cavity may be damaged.
Under the circumstances, a device for automatically adjusting body cavity pressure is required in order to eliminate the above-noted inconveniences.